Confocal microscope

ABSTRACT

A diffraction limited confocal microscope (30) includes an energy source (31) to provide focussable illuminating energy and a single mode energy guide (34) comprising a core, an energy receiver (33) and an energy exit (35). The energy guide is operatively associated with the energy source so that illuminating energy from the energy source is received by the energy receiver and coupled into the core and guided to the energy exit so as to emerge from the core at the energy exit. A first focusser (39) is operatively associated with the energy exit to focus at least a portion of the illuminating energy emerging from the core into a diffraction limited spot pattern volume having a central portion which in use intersects an object (40). A second focusser (39) is operatively associated with the first focusser to collect outgoing energy from the volume resulting from interaction between the illuminating energy in the volume and the object and/or resulting from transmission or reflection of illuminating energy from the volume. The microscope includes a detector (45) having an aperture and a detecting element wherein the detector is operatively associated with the second focusser whereby the second focusser images the aperture onto the central portion wherein the numerical aperture, NA, of the outgoing energy originating from the central portion focussed onto the aperture, the wavelength of the outgoing energy, λ, and the average diameter, d, of the aperture are related by the equation: NA≦0.6×λ/d whereby the detector detects the outgoing energy.

TECHNICAL FIELD

This invention relates to a diffraction limited confocal microscope, adiffraction limited reflection confocal microscope and a method ofscanning an object.

BACKGROUND ART

A schematic drawing of a conventional reflection confocal microscope isshown in FIG. 1. Laser light from laser 1 is focussed onto mechanicalpinhole 3 by microscope objective 2. The expression "mechanical pinhole"in this specification means a conventional pinhole in a sheet which istypically of metal. The expanding light beam from pinhole 3 iscollimated by lens 4 before passing through polarizing beam splitter 8,which polarizes the beam, and quarter waveplate 7, which makes the beamcircularly polarized. The beam is then focussed into a diffractionlimited spot on object 6 by high quality microscope objective 5. Lightreflected and scattered by object 6 is collected by objective 5 whichcollimates the beam. Light reflected by object 6 remains circularlypolarized so that when it passes back through quarter waveplate 7 it isagain linearly polarized, but in the direction perpendicular to theoriginal polarized beam. The polarization of light scattered by object 6being random, will be unaffected by quarter waveplate 7. The lightreflected by object 6, with its polarization now rotated by 90 degrees,is redirected by polarizing beam splitter B. A portion of the lightscattered by object 6 will also be redirected by polarizing beamsplitter 8. The redirected light is focussed onto detector pinhole 10 byimaging element 9. A detector 11 measures the amount of light thatpasses through the pinhole 10. Object 6 is scanned mechanically in thex, y and z directions by stage 12.

The basis of operation of a reflection confocal microscope can be seenby examination of FIG. 2 which is a schematic drawing of a simplifiedconfocal microscope arrangement. A mechanical pinhole point source oflight 15 is imaged onto object 17 by a high quality optical element 16.The illuminating pinhole size 15 is chosen such that light strikingobject 17 forms a diffraction limited spot pattern whose size isdetermined by the wavelength of light and the characteristics of highquality optical element 16. The light reflected and scattered by thesurface is collected by the high quality optical element 16 andredirected by beam splitter 13 onto a pinhole detector 14. For maximumresolution the size of the pinhole at detector 14 is chosen to beslightly smaller than the first minimum of the diffraction limited spotimaged onto it.

The confocal arrangement described above in FIG. 2 results in aresolution gain of approximately 0.4 over that of conventionalmicroscopes. By using an annulus, this resolution gain is increased toapproximately 0.7 over that of a conventional microscope. Additionally,the confocal microscope has a much reduced depth of field, when comparedto that of conventional microscopes, which enables out-of-focusinformation to be removed from the image. This enables rough, curved orpartially transparent surfaces to be properly imaged.

In order to obtain an image of an object, the object (or the microscope)is scanned in x, y and z directions with the maximum signal during a zscan being chosen as the intensity at the x, y position. For partiallytransparent objects, such as biological cells, three dimensionalinformation can be extracted. There is no limit to the size of the areathat can be imaged without compromising the resolution. It should benoted that the signal from a confocal microscope is readily amenable toelectronic image enhancement.

Mechanical pinholes are susceptible to dirt lodging in the aperture.Even the smallest amount of dirt in a mechanical pinhole in a confocalmicroscope creates a problem as the resultant light field is no longercircularly symmetrical and aberrations are introduced. Further, slightmisalignment of a mechanical pinhole or any other element in aconventional confocal microscope causes asymmetric intensitydistribution of the light beam emerging from the mechanical pinholeagain causing aberrations.

OBJECTS OF INVENTION

Each of these objects is accomplished by use of an optical fiber.

It is an object of this invention to provide a diffraction limitedconfocal microscope.

Another object is to provide a diffraction limited reflection confocalmicroscope.

A further object is to provide a method of scanning an object.

DISCLOSURE OF INVENTION

According to a first embodiment of this invention there is provided adiffraction limited confocal microscope comprising:

an energy source to provide focussable illuminating energy;

a single mode energy guide comprising a core, an energy receiver and anenergy exit;

the energy guide being operatively associated with the energy source sothat illuminating energy from the energy source is received by theenergy receiver and coupled into the core and guided to the energy exitso as to emerge from the core at the energy exit;

a first focusser operatively associated with the energy exit to focus atleast a portion of the illuminating energy emerging from the core into adiffraction limited spot pattern volume having a central portion whichin use intersects an object;

a second focusser operatively associated with the first focusser, and inuse with the object, to collect outgoing energy from the volumeresulting from interaction between the illuminating energy in the volumeand the object and/or resulting from transmission of illuminating energythrough the volume;

a detector having an aperture and a detecting element;

wherein the detector is operatively associated with the second focusserwhereby the second focusser images the aperture onto the central portionwherein the numerical aperture, NA, of the outgoing energy originatingfrom the central portion focussed onto the aperture, the wavelength ofthe outgoing energy, λ, and the average diameter, d, of the aperture arerelated by the equation:

    NA≲0.6×λ/d

whereby the detector detects the outgoing energy.

The aperture can be a pinhole aperture.

The aperture may be the core at an energy receiving end of a secondenergy guide having a core which also has an energy exit operativelyassociated with said detecting element to detect outgoing energyfocussed into the core of the second energy guide.

The energy guide operatively associated with the detector may be amultimode energy guide or a single mode energy guide.

According to a second embodiment of this invention there is provided adiffraction limited confocal microscope comprising:

an energy source to provide focussable illuminating energy;

a single mode energy guide comprising a core, an energy receiver and anenergy exit;

the energy guide being operatively associated with the energy source sothat illuminating energy from the energy source is received by theenergy receiver and coupled into the core and guided to the energy exitso as to emerge from the core at the energy exit;

a first focusser operatively associated with the energy exit to focus atleast a portion of the illuminating energy emerging from the core into adiffraction limited spot pattern volume which in use intersects anobject;

a second focusser operatively associated with the first focusser, and inuse with the object, to collect outgoing energy from the volumeresulting from interaction between the illuminating energy in the volumeand the object and/or resulting from transmission of illuminating energythrough the volume;

a detector having a detecting element,

wherein the detector is operatively associated with the second focusserwhereby the second focusser images the detecting element onto a centralportion of the illuminating energy in the volume wherein the numericalaperture, NA, of the outgoing energy originating from the centralportion focussed onto the detecting element, the wavelength of theoutgoing energy, λ, and the average diameter, d, of the detectingelement are related by the equation:

    NA≲0.6×λ/d

whereby the detector detects the outgoing energy.

Typically the microscope of the first and second embodiments furtherinclude an energy splitter provided in the energy path between the coreat the energy exit and the volume, to direct the outgoing energy to thedetector and wherein the illuminating and outgoing energy paths aresubstantially the same between the volume and the splitter.

Generally the first focusser and the second focusser have common energyfocussing elements.

The energy splitter may be a wavelength dependent splitter.

Generally the microscope of the second embodiment further includes apolarizer, operatively associated with the energy source, to polarizethe illuminating energy and wherein said energy splitter is polarizationdependent.

The microscope of the second embodiment may also include a polarizationdevice disposed in the path of the polarized illuminating energy and theoutgoing energy between the polarization dependent energy splitter andthe volume, to at least partially circularly polarize the illuminatingenergy and to at least partially linearly polarize the outgoing energypassing back through the polarization dependent energy splitter.

According to a third embodiment of this invention there is provided adiffraction limited reflection confocal microscope comprising:

an energy source to provide focussable illuminating energy;

a single mode energy guide comprising a core, an energy receiver and anenergy exit;

the energy guide being operatively associated with the energy source sothat illuminating energy from the energy source is received by theenergy receiver and coupled into the core and guided to the energy exitso as to emerge from the core at the energy exit;

a focusser operatively associated with the energy exit to focus at leasta portion of the illuminating energy emerging from the core into adiffraction limited spot pattern volume having a central portion whichin use intersects an object, to collect outgoing energy resulting frominteraction between the illuminating energy in the volume and the objectand to direct at least a portion of the outgoing energy into the core atthe energy exit;

a detector; and

an energy emanator operatively associated with the guide and thedetector to extract the outgoing energy from the core and direct theoutgoing energy to the detector;

wherein the focusser images the core at the energy exit onto the centralportion wherein the numerical aperture, NA, of the outgoing energyoriginating from the central portion focussed onto the core at theenergy exit, the wavelength of the outgoing energy, λ, and the averagediameter, d, of the core at the energy exit are related by the equation:

    NA≲0.6×λ/d

The following comments apply to the third embodiment.

The diffraction limited reflection confocal microscope of the thirdembodiment can include scanning means operatively associated with theenergy guide adjacent the exit end to move the exit end in the x and/ory and/or z directions to scan the diffraction limited spot patternvolume in and about the object The scanning means can be a piezoelectricstack, a magnetic core/magnetic coil combination, a mechanical vibrator,an electromechanical vibrator, a mechanical or electromechanicalscanning mechanism such as a servomotor, an acoustic coupler or anyother suitable means.

Generally, the receiver and the emanator have a energy splitter incommon which enables a portion of the illuminating energy from thesource to be directed into the core of the energy guide and enables aportion of the outgoing energy in the core of the energy guide to bedirected to the detector. Typically, said energy splitter comprises awavelength dependent energy splitter. The energy splitter may be anenergy guide coupler such an a optical fibre coupler. The optical fibrecoupler may be a fused biconical taper coupler, a polished blockcoupler, a bottled and etched coupler or a bulk optics type coupler withfibre entrance and exit pigtails, a planar waveguide device based onphotolithographic or ion-diffusion fabrication techniques or other likecoupler.

Also the reflection confocal microscope may further include a polarizer,operatively associated with the energy source, to polarize theilluminating energy and said energy splitter is polarization dependent.A polarization device disposed in the path of the polarized illuminatingenergy and the outgoing energy between the polarization dependent energyspitter and the volume, to at least partially circularly polarize theilluminating energy and to at least partially linearly polarize theoutgoing energy passing back through the polarization dependent energysplitter can also be included.

In one particular arrangement a polarizer can be disposed between theilluminating energy source and a polarization dependent energy splitter,or the energy source may be inherently polarized, or the polarizationdependent energy splitter polarizes the illuminating energy passingtherethrough, whereby illuminating energy emanating from the splitter islinearly polarized illuminating energy. In this arrangement apolarization device such as a quarter wave device is disposed in thepath of the polarized illuminating energy and the outgoing energybetween the polarization dependent energy splitter and the object tocircularly polarize the illuminating energy and to linearly polarize theoutgoing energy passing back through the polarization dependent energysplitter in the direction perpendicular to the linearly polarizedilluminating energy.

An energy scanner may be operatively associated with the energy exit andthe focusser to move the image of the core at the energy exit relativeto the focusser to scan the volume in and about the object. Typicallythe energy scanner is a movable energy reflector, an electro-energydevice or an acousto-energy device.

A scanner may be operatively associated with the focusser to move thefocusser with respect to the energy exit to scan the volume in and aboutthe object.

In the first to third embodiments a scanner may be operativelyassociated with the energy exit and the focusser to move the combinationof the energy exit and the focusser with respect to the object to scanthe volume in and about the object In a further alternative a scanner isincluded which in use is operatively associated with the object to movethe object in the x and/or y and/or z directions to scan the volume inand about the object

The first to third embodiments may further include apparatus operativelyassociated with the detector, for storing and analysing a signal fromthe detector to provide information in respect of the object.

If the first to third embodiments have a scanner they may also includeapparatus operative-y associated with the detector and the scanner, forstoring and analysing a signal from the detector and a signal from thescanner, which, in use, is indicative of the location of the entitybeing moved by the scanner, to provide information in respect of theobject.

The storage and analysing apparatus is typically a computer. Thecomputer can provide surface profile information and to obtain a highresolution in-focus image of a rough surface for example.

According to a fourth embodiment of this invention there is provided amethod of scanning an object to provide information thereof comprising:

(a) focussing illuminating energy from the core at the energy exit of asingle mode energy guide comprising a core, an energy receiver and anenergy exit, into a diffraction limited spot pattern volume having acentral portion which intersects the object;

(b) imaging the core onto the central portion of the volume and therebycollecting outgoing energy resulting from interaction between theilluminating energy in the volume and the object, wherein the numericalaperture, NA, of the outgoing energy originating from the centralportion focussed onto the core, the wave length of the outgoing energy,λ, and the average diameter, d, of the core at the exit end are relatedby the equation:

    NA≲0.6×λ/d

c) detecting the outgoing energy entering the core at the exit end toprovide a signal indicative of the interaction;

d) refocussing illuminating energy from the core at the energy exit of asingle mode energy guide to focus at least a portion of the centralregion in another volume intersected by the object;

e) repeating steps (b) and (c); and

f) repeating steps (d) and (e).

Typically the method of the fourth embodiment further includes storingand analysing the detected signal to provide information in respect ofthe object

Alternatively, the method of the fourth embodiment may include storingand analysing the detected signal and the position of the volume withrespect to the object to provide information in respect of the object.

Generally, in the first to fourth embodiments the numerical aperture,NA. of the outgoing energy originating from the central portion focussedonto the aperture, the wavelength of the outgoing energy, λ, and theaverage diameter, d, of the aperture, detector element or core arerelated by the equation:

    NA<0.6×λ/d

The following comments apply to the first to fourth embodiments.

The energy guide can be flexible and can be an energy fibre.

The energy source can provide a solid particle beam, such as a neutron,proton or electron beam or a beam of alpha particles, acoustic waves,such as sound waves, or electromagnetic radiation, such as gamma rays,x-rays, UV light, visible light, infrared light or microwaves. Generallythe energy source is a source of electromagnetic radiation with awavelength in the range of and including far UV to far IR and the energyguide is an optical fibre.

Examples of light sources include incandescent sources, such as tungstenfilament source, vapour lamps such as halogen lamps including sodium andiodine vapour lamps, discharge lamps such as xenon arc lamp and a Hg arclamp, solid state light sources such as photo diodes, super radiantdiodes, light emitting diodes, laser diodes, electroluminiscent lightsources, laser light sources including rare gas lasers such as an argonlaser, argon/krypton laser, neon laser, helium neon laser, xenon laserand krypton laser, carbon monoxide and carbon dioxide lasers, metal ionlasers such as cadmium, zinc, mercury or selenium ion lasers, lead saltlasers, metal vapour lasers such as copper and gold vapour lasers,nitrogen lasers, ruby lasers, iodine lasers, neodymium glass andneodymium YAG lasers, dye lasers such as a dye laser employing rhodamine640, Kiton Red 620 or rhodamine 590 dye, and a doped fibre laser.

The energy guide can be a flexible, single mode optical fibre. Forexample, a five micron core fibre which is single mode at a wave lengthof 633 nanometers given an appropriate refractive index profile. A stepindex optical fibre becomes single mode when the numerical aperture, NA,the fibre core radius, a, and the wave length of light, λ, obey therelationship:

    2×π×NA×a/λ≦2.405.

The focusser can be refractive glass lenses, including microscopeobjectives, reflective lenses, and/or holographic optical elements. Ifthe energy is of a frequency other than in the range of UV to nearinfrared light or other types of energies, analogous focussing elementsare used in place of the optical focussing elements.

A particular diffraction limited confocal microscope of the presentinvention utilizes a single mode optical fibre/light source in place ofa mechanical pinhole/light source combination. As already pointed outmechanical pinholes are particularly susceptible to dirt lodging in theaperture. Even the smallest amount of dirt in the aperture of amechanical pinhole creates a problem as a light beam emerging from sucha pinhole is no longer circularly symmetrical and aberrations areintroduced into the system. Whilst dirt can lodge on the light entry andexit ends of an optical fibre it is relatively easy to clean and ifnecessary, can be recleaved

As already pointed out above, a mechanical pinhole/light sourcecombination is difficult to align accurately. If a mechanical pinhole isnot properly aligned, the resolution of the confocal microscope isseverely affected and anomalous diffraction spot geometries result whichhave serious consequences in respect of the accuracies of depth studiesand other studies. On the other hand, if a single mode opticalfibre/light source combination is not properly aligned, whilst the lightintensity of a light beam emerging from the exit end of the fibredecreases, the emerging light beam is still circularly symmetrical.

When an integral single mode optical fibre/light source combination isutilized in a reflection confocal microscope the problem of aligning theoptical fibre with the light source which is a relatively difficult taskis effectively eliminated. This latter combination also reduces thenumber of discrete optical components that require mounting in theconfocal microscope. In addition, if an integral single mode opticalfibre/laser diode combination is used, a laser diode with an integralfeedback detector can be utilized which enables monitoring and controlof the power output of the laser diode. Analogously utilization of anintegral optical fibre/detector effectively eliminates the need foraligning the optical fibre with the detector.

A further advantage of a single mode optical fibre/light source andoptical fibre/detector combination in a reflection confocal microscopeis that the light source and detector and associated electronics can beremotely located from the optical hardware such as the polarizer andfocussing lens or focussing lens system. Of particular advantage is thefact that the light source and detector when located remote from theobject can be easily temperature controlled increasing lifetime,accuracy and reliability, which is particularly useful in harshindustrial environments.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 a schematic drawing of a conventional diffraction limitedconfocal microscope;

FIG. 2 is a schematic drawing of a simplified diffraction limitedconfocal microscope arrangement;

FIG. 3 is a schematic drawing of a diffraction limited confocalmicroscope according to the present invention;

FIG. 4 is a schematic drawing of another diffraction limited confocalmicroscope according to the present invention:

FIG. 5 is a schematic drawing of a further diffraction limited confocalmicroscope according to the present invention; and

FIG. 6 is another schematic drawing of a diffraction limited reflectionconfocal microscope arrangement.

BEST MODE AND OTHER MODES FOR CARRYING OUT THE INVENTION

Referring to FIG. 3 a diffraction limited reflection confocal microscope30 has a laser 31 disposed on one side of focussing element 32. Laserlight from laser 31 falls on element 32 and is focussed onto lightreceiving end 33 of single mode optical fibre 34. Fibre 34 has a lightexit end 35. A collimating lens 36 is operatively disposed in relationto exit end 35 to collimate illuminating laser light emerging therefrom.Polarizing beam splitter 37 is operatively disposed in relation tocollimating lens 36 to polarize collimated illuminating laser lighttherefrom. A quarter waveplate 38 is operatively disposed in relation tothe polarizer to circularly polarize polarized illuminating laser lightemerging from beam splitter 37. A high quality microscope objective 39is operatively disposed in relation to waveplate 38 to focus circularlypolarized illuminating laser light which has passed through waveplate 38into a diffraction limited spot pattern volume intersecting object 40.Outgoing light resulting from interaction between illuminating laserlight in the volume and object 40 is collected by objective 39 andcollimated to form collimated outgoing light. The collimated outgoinglight passes through quarter waveplate 38. Outgoing light from object 40passes through quarter waveplate 38 A portion of this outgoing light isreflected by polarizing beam splitter 37 onto focussing lens 41.Focussing lens 41 is operatively disposed in relation to beam splitter37 to focus outgoing light reflected by beam splitter 37 onto lightreceiving end 42 of second optical fibre 43. Focussing lens 41 andobjective 39 are arranged to image the core of the light receiving end42 of fibre 43 onto the central portion of the illuminating laser lightdiffraction limited spot pattern wherein the numerical aperture, NA, ofthe outgoing light originating from the central portion focussed ontothe fibre core, the wavelength of the outgoing light, λ, and the averagediameter, d, of the fibre core at light receiving end 42 of fibre 43 arerelated by the equation:

    NA=0.36×λ/d.

Photodetector 45 is disposed to detect outgoing light emerging from exitend 44 of second optical fibre 43.

In use illuminating laser light from laser 31 falls on focussing element32 which focusses illuminating laser light onto light receiving end 33of single mode optical fibre 34. The illuminating laser light collectedby the core of light receiving end 33 of fibre 34 passes through fibre34 and emerges from exit end 35. Exit end 35 effectively acts as apinhole. Illuminating laser light emerging from exit end 35 passedthrough collimating lens 36 which collimates the illuminating laserlight. The collimated illuminating laser light passed through beamsplitter 37 and emerges as linearly polarized collimated illuminatinglaser light. The linearly polarized collimated illuminating laser lightthen passes through waveplate 38. Collimated illuminating laser lightemerging from waveplate 38 is circularly polarized and passes throughmicroscope objective 39 which focusses the illuminating laser light intoa diffraction limited spot pattern volume intersecting object 40.Outgoing light resulting from interaction between the illuminating laserlight in the volume and object 40 is collected by objective 39 andcollimated. The collimated outgoing light passes through quarterwaveplate 38. Outgoing light reflected by the object 40 having passedthrough quarter waveplate 38 is now linearly polarized perpendicular tothe linearly polarized illuminating laser light. Therefore it isreflected by polarizing beam splitter 37 onto focussing lens 41.Outgoing light scattered by object 40 having a random polarization issubstantially unaffected by waveplate 38. A portion of this outgoinglight is reflected by polarizing beam splitter 37 onto focussing lens41. Lens 41 focusses outgoing light reflected by beam splitter 37 ontolight receiving end 42 of second optical fibre 43. The outgoing lightcollected by the core of the light receiving end 42 passes throughsecond optical fibre 43 and is detected by photodetector 45 on emergingfrom exit end 44. Surface profile information in connection with object40 is typically obtained by moving objects 40 back and forward. In someinstances, it is preferable to move microscope objective 39 back andforward instead of moving object 40. The position when maximum light isdetected at detector 45 typically corresponds to the position of thesurface of object 40. Object 40 can then be moved to a differentposition in the x-y plane and the process repeated. Again in someinstances it is preferable to move microscope objective 39 in the x-yplane. The entire surface of object 40 can be mapped by repeating theabove procedure for different x-y positions of object 40. Asuperresolving filter(s) may be placed virtually anywhere in theilluminating and/or detecting paths in order to improve x and/or yand/or z resolution.

The alternative diffraction limited reflection confocal microscope 50illustrated in FIG. 4 is the same as confocal microscope 30 depicted inFIG. 3 except laser/focussing element/fibre entrance end 31, 32 and 33are replaced by laser diode 51 having an integral single mode fibreoptic pigtail 52 and fibre end/detector combination 44 and 45 arereplaced by detector 53 and having an integral fibre optic pigtail 54.

The advantages of microscope 50 over microscope 30 depicted in FIG. 3are that focussing element 32 is eliminated and there is no need toalign laser 31 with light receiving end 33 of single mode fibre 34.Because integral fibre optic pigtail 52 is hermetically sealed in thesame package as diode laser 51 dirt cannot enter the optical pathbetween laser diode 51 and integral single mode optical fibre pigtail52. In addition laser diode 51 typically has an integral feedbackdetector which thereby enables the power output of the laser to bedetermined. The advantages associated with the integral fibre opticpigtail 54 associated with photodetector 53 are that there is no need tolocate the detector with respect to the fibre and dirt cannot enter theoptical path as is the case where dirt can enter the optical pathbetween exit end 44 and detector 45 in the embodiment depicted in FIG.3.

In a further alternative diffraction limited reflection confocalmicroscope 60 illustrated in FIG. 5 super radiant diode 61 with integralsingle mode optical fibre pigtail 62 is fused to port 63 of directionalsingle mode fibre directional coupler 64. Illuminating light fromintegral fibre optic pigtail 62 is split between port 65 and 66. Port 65of coupler 64 is terminated at end 66A to prevent back reflections.Alternatively fibre end 66A could be coupled to a detector to monitorthe light power of super radiant diode 61. Illuminating light emergingfrom singe mode fibre exit end 68 of fibre 69 is collected by microscopeobjective 70 which has a finite tube length, and which is operativelydisposed in relation to exit end 68 and object 71 to form a diffractionlimited spot pattern volume intersecting object 71. Outgoing lightresulting from interaction between illuminating light in the volume andobject 71 is collected by objective 70 and focussed back onto fibre end68. Microscope objective 70 images the core of the fibre end 68 onto thecentral portion of the illuminating light diffraction limited spotpattern wherein the numerical aperture, NA, of the outgoing lightoriginating from the central portion focussed onto the fibre core, thewavelength of the outgoing light, λ, and the average diameter, d, of thefibre core at light exit end 68 of fibre 69 are related by the equation:

    NA=0.3×λ/d.

Outgoing light collected by the core of fibre 69 is split between ports63 and 72 of single mode fibre directional coupler 64. Outgoing lightfrom port 72 passes through integral fibre optic pigtail 67 to detector73. Piezoelectric stack 75 is coupled to fibre 69 adjacent to fibre end68.

In use illuminating light from super radiant diode 61 passes throughintegral single mode optical fibre pigtail 62 to port 63 of coupler 64.Coupler 64 splits the illuminating light between ports 65 and 66.Illuminating light passes from port 66 through fibre 69 and emerges fromsingle mode fibre exit end 68 and is collected by microscope objective70 which focusses the illuminating light into a diffraction limited spotpattern volume intersecting object 71. Outgoing light results frominteraction between the illuminating light in the volume and the objectand is collected by objective 70 and is focussed onto single mode fibreexit end 68. Light collected by the core at fibre exit end 68 passesthrough fibre 69 to port 66 of coupler 64. This outgoing light is splitbetween ports 63 and 72 of coupler 64. Light from port 72 passes throughintegral optical fibre pigtail 67 and is detected by photodiode 73.

Microscope 60 can be utilized to obtain surface profile information inconnection with object 71 or information within the volume of object 71,by moving fibre end 68 back and forward along the axis of theilluminating system (z direction}using piezoelectric stack 75. Theposition when maximum light is detected at detector 73 typicallycorresponds to the surface of object 71. It is also possible to scanobject 71 in the x-y plane by moving fibre end 68 in the x-y plane. Asfor microscopes 30 and 50, in microscope 60 object 71 can also beprofiled by moving the objective 70 and/or the object 71 in the x-y andz directions. In this manner the entire surface of object 71 can bemapped.

The advantages of microscope 60 over microscopes 50 and 30 are:

1. Because of the small mass of fibre 69 the object can be scanned veryrapidly.

2. Fewer optical elements are required in microscope 60 as compared withmicroscopes 30 and 50. Apart from economic savings in respect of feweroptical elements since the only two elements that have to be opticallylocated with respect to each other are fibre end 68 and objective 70simpler mounting structures are required.

3. It is very simple to align microscope 60 as compared to microscopes30 and 50. This is a consequence of fibre end 68 serving as both thefibre source and the fibre detector. Further, it is very difficult tomisalign exit end 68.

If directional coupler 64 is a polarization splitting coupler and superradiant diode 61 is disposed such that illuminating polarized lightentering port 63 is predominantly directed to port 66, a higherilluminating intensity occurs at object 71. Furthermore, if a quarterwaveplate 74 is placed between fibre exit end 68 and objective 70,outgoing light entering fibre exit end 68 predominantly emerges fromport 72 and onto photodiode 73. This is because a laser diode typicallyemits polarized light. By orienting super radiant diode 61/integralfibre optic pigtail 62 correctly with respect to polarization beamsplitting coupler 64 the illuminating light passes predominantly out ofcoupler port 66, through fibre 69 and emerges polarized from fibre end68. The linearly polarized illuminating light is circularly polarizedafter passing through quarter waveplate 74. Illuminating light reflectedby object 71, when it passes back through quarter waveplate 74, becomeslinearly polarized perpendicular to that of the illuminating light.Therefore this outgoing light, which passes through fibre 69 into port66 of the polarizing beam splitting coupler 64 passes predominantly outthrough port 72 along fibre 67 and is detected by photodiode 73.

The advantage of including quarter waveplate 74 and using a polarizingbeam splitting coupler 64 is that the signal resulting from an object 71which reflects a portion of the illuminating light is increased.

The alternative diffraction limited reflection confocal microscope 80depicted in FIG. 6 is the same as confocal microscope 60 shown in FIG. 5except optical element 81 is placed between fibre exit end 82 andquarter waveplate 83. Further, microscope objective 84 is an infinitycorrected microscope objective. The advantage of microscope 80 overmicroscope 60 is that it is difficult to maintain diffraction limitedoperation in microscope objective 70 with quarter waveplate 74 present.In microscope 80 of FIG. 6 the inclusion of optical element 81 avoidsthe introduction of aberrations into the illuminating light and theoutgoing light by waveplate 83.

INDUSTRIAL APPLICABILITY

A diffraction limited confocal microscope of the invention can be usedin environments where vibration is a problem for conventional confocalmicroscopes since it can be aligned more easily and there are fewerparts to maintain in alignment. In addition, the illumination anddetection optics and electronics of a confocal microscope of theinvention can be placed at a distance from the actual optical focussingtrain of the microscope thus enabling it to be operated in electricallynoisy environments without the need for complex electrical shielding. Ina particular embodiment of a confocal microscope of the invention,because of the use of the novel arrangement of the single optical fibresource/detector aperture, it is not susceptible to minor misalignmentresulting in asymmetric pinhole placement and therefore, unlike aconventional confocal microscope, continuous monitoring of the pinholeposition is not necessary. Since an energy guide, and when light is usedas the energy source, an optical fibre, is used as the illuminatinglight guide in a confocal microscope of this invention, such amicroscope is more easily maintained and more reliable since energyguides and in particular, optical fibres are less susceptible to dirtcontamination than the mechanical pinholes which are utilized in aconventional confocal microscope. Further, since there are fewer partsrequired in a confocal microscope of the invention it is inherentlycheaper to manufacture and maintain. Moreover, in the case where asingle optical fibre source/detector aperture is utilized in a confocalmicroscope of the invention it is possible to rapidly scan an object bysimply vibrating the exit end of the fibre. This permits a confocalmicroscope of the invention to be utilized for more rapid imaging thanconventional confocal microscopes while maintaining high resolution,diffraction limited operation.

I claim:
 1. A diffraction limited confocal microscope comprising:a lightsource to provide focussable illuminating energy; a single mode energyguide comprising a core, an energy receiver and an energy exit: theenergy guide being operatively associated with the light source so thatilluminating energy from the light source is received by the energyreceiver and coupled into the core and guided to the energy exit so asto emerge from the core at the energy exit; a first focusser operativelyassociated with the energy exit to focus at least a portion of theilluminating energy emerging from the core into a diffraction limitedspot pattern volume having a central portion which in use intersects anobject; a second focusser operatively associated with the firstfocusser, and in use with the object, to collect outgoing energy fromthe volume resulting from interaction between the illuminating energy inthe volume and the object and/or resulting from transmission ofilluminating energy through the volume; a detector having an apertureand a detecting element; wherein the detector is operatively associatedwith the second focusser whereby the second focusser images the apertureonto the central portion wherein the numerical aperture, NA, of theoutgoing energy originating from the central portion focussed onto theaperture, the wavelength of the outgoing energy, λ, and the averagediameter, d, of the aperture are related by the equation:

    NA≲0.6×λ/d

whereby the detector detects the outgoing energy.
 2. A diffractionlimited confocal microscope according to claim 1 wherein said numericalaperture, NA, of the outgoing energy originating from the centralportion focussed onto the aperture, the wavelength of the outgoingenergy, λ, and the average diameter, d, of the aperture are related bythe equation:

    NA<0.6×λ/d.


3. A diffraction limited confocal microscope according to claim 1wherein said aperture is a pinhole aperture
 4. A diffraction limitedconfocal microscope according to claim 1 wherein said aperture is thecore at an energy receiving end of a second energy guide having a corewhich also has an energy exit operatively associated with said detectingelement to detect outgoing energy focussed into the core of the secondenergy guide.
 5. A diffraction limited confocal microscope according toclaim 4 wherein said second energy guide is a single mode energy guide.6. A diffraction limited confocal microscope comprising:light source toprovide focussable illuminating energy; a single mode energy guidecomprising a core, an energy receiver and an energy exit; the energyguide being operatively associated with the light source so thatilluminating energy from the light source is received by the energyreceiver and coupled into the core and guided to the energy exit so asto emerge from the core at the energy exit; a first focusser operativelyassociated with the energy exit to focus at least a portion of theilluminating energy emerging from the core into a diffraction limitedspot pattern volume which in use intersects an object; a second focusseroperatively associated with the first focusser, and in use with theobject, to collect outgoing energy from the volume resulting frominteraction between the illuminating energy in the volume and the objectand/or resulting from transmission of illuminating energy through thevolume; a detector having a detecting element; wherein the detector isoperatively associated with the second focusser whereby the secondfocusser images the detecting element onto a central portion of theilluminating energy in the volume wherein the numerical aperture, NA, ofthe outgoing energy originating from the central portion focussed ontothe detecting element, the wavelength of the outgoing energy, λ, and theaverage diameter, d, of the detecting element are related by theequation:

    NA≲0.6×λ/d

whereby the detector detects the outgoing energy.
 7. A diffractionlimited confocal microscope according to claim 6 wherein said numericalaperture, NA, of the outgoing energy originating from the centralportion focussed onto the element, the wavelength of the outgoingenergy, λ, and the average diameter, d, of the element are related bythe equation:

    NA<0.6×λ/d.


8. A diffraction limited confocal microscope according to claim 1further comprising an energy splitter provided in the energy pathbetween the core at the energy exit and the volume, to direct theoutgoing energy to the detector and wherein the illuminating andoutgoing energy paths are substantially the same between the volume andthe splitter.
 9. A diffraction limited confocal microscope according toclaim 8 wherein the first focusser and the second focusser have commonenergy focussing elements.
 10. A diffraction limited confocal microscopeaccording to claim 8 wherein said energy splitter comprises a wavelengthdependent splitter.
 11. A diffraction limited confocal microscopeaccording to claim 8 further comprises a polarizer, operativelyassociated with the energy source, to polarize the illuminating energyand wherein said energy splitter is polarization dependent.
 12. Adiffraction limited confocal microscope according to claim 11 furthercomprising a polarization device disposed in the path of the polarizedilluminating energy and the outgoing energy between the polarizationdependent energy splitter and the volume, to at least partiallycircularly polarize the illuminating energy and to at least partiallylinearly polarize the outgoing energy passing back through thepolarization dependent energy splitter.
 13. A diffraction limitedreflection confocal microscope comprising:a light source to providefocussable illuminating energy; a single mode energy guide comprising acore, an energy receiver and an energy exit; the energy guide beingoperatively associated with the light source so that illuminating energyfrom the light source is received by the energy receiver and coupledinto the core and guided to the energy exit so as to emerge from thecore at the energy exit; a focusser operatively associated with theenergy exit to focus at least a portion of the illuminating energyemerging from the core into a diffraction limited spot pattern volumehaving a central portion which in use intersects an object, to collectoutgoing energy resulting from interaction between the illuminatingenergy in the volume and the object and to direct at least a portion ofthe outgoing energy into the core at the energy exit; a detector; and anenergy emanator operatively associated with the guide and the detectorto extract the outgoing energy from the core and direct the outgoingenergy to the detector; wherein the focusser images the core at theenergy exit onto the central portion wherein the numerical aperture, NA,of the outgoing energy originating from the central portion focussedonto the core at the energy exit, the wavelength of the outgoing energy,λ, and the average diameter, d, of the core at the energy exit arerelated by the equation:

    NA≲0.6×λ/d.


14. A diffraction limited reflection confocal microscope according toclaim 13 wherein said numerical aperture, NA, of the outgoing energyoriginating from the central portion focussed onto the core at the exitend, the wavelength of the outgoing energy, λ, and the average diameter,d, of the core at the exit end, are related by the equation:

    NA<0.6×λ/d.


15. A diffraction limited reflection confocal microscope according toclaim 13 further comprising a scanner operatively associated with theenergy guide to move the energy exit in the x and/or y and/or zdirections to scan the diffraction limited spot pattern volume in andabout the object.
 16. A diffraction limited reflection confocalmicroscope according to claim 15 wherein said scanner is a piezoelectricstack, a magnetic core/magnetic coil combination, a mechanical vibrator,an electromechanical vibrator, a mechanical or electromechanicalpositioning mechanism or an acoustic coupler.
 17. A diffraction limitedreflection confocal microscope according to claim 13 wherein thereceiver and the emanator have a energy splitter in common which enablesa portion of the illuminating energy from the source to be directed intothe core of the energy guide and enables a portion of the outgoingenergy in the core of the energy guide to be directed to the detector.18. A diffraction limited reflection confocal microscope according toclaim 17 wherein said energy splitter comprises a wavelength dependentenergy splitter.
 19. A diffraction limited reflection confocalmicroscope according to claim 17 further comprising a polarizer,operatively associated with the energy source, to polarize theilluminating energy and wherein said energy splitter is polarizationdependent.
 20. A diffraction limited reflection confocal microscopeaccording to claim 19, further comprising a polarization device disposedin the path of the polarized illuminating energy and the outgoing energybetween the polarization dependent energy splitter and the volume, to atleast partially circularly polarize the illuminating energy and to atleast partially linearly polarize the outgoing energy passing backthrough the polarization dependent energy splitter.
 21. A diffractionlimited reflection confocal microscope according to claim 17 whereinsaid energy splitter comprises an energy guide coupler.
 22. Adiffraction limited reflection confocal microscope according to claim 21wherein said energy guide coupler is a fused biconical taper coupler, apolished block coupler, a bottled and etched coupler, a bulk optics typecoupler with fibre entrance and exit pigtails or a planar waveguidedevice based on photolithographic or ion-diffusion fabricationtechniques.
 23. A diffraction limited reflection confocal microscopeaccording to claim 13 comprising an energy scanner operativelyassociated with the energy exit and the focusser to move the image ofthe core at the energy exit relative to the focusser to scan the volumein and about the object.
 24. A diffraction limited reflection confocalmicroscope according to claim 23 wherein the energy scanner is a movableenergy reflector, an electro-energy device or an acousto-energy device.25. A diffraction limited reflection confocal microscope according toclaim 13 further comprising a scanner operatively associated with thefocusser to move the focusser with respect to the energy exit to scanthe volume in and about the object.
 26. A diffraction limited reflectionconfocal microscope according to claim 13 further comprising a scanneroperatively associated with the energy exit and the focusser to move thecombination of the energy exit and the focusser with respect to theobject to scan the volume in and about the object.
 27. A microscopeaccording to claim 1 further comprising a scanner which in use isoperatively associated with the object to move the object in the xand/or y and/or z directions to scan the volume in and about the object.28. A microscope according to claim 1 further comprising apparatusoperatively associated with the detector, for storing and analysing asignal from the detector to provide information in respect of theobject.
 29. A microscope according to claim 15, further comprisingapparatus operatively associated with the detector and the scanner, forstoring and analysing a signal from the detector and a signal from thescanner, which, in use, is indicative of the location of the entitybeing moved by the scanner, to provide information in respect of theobject.
 30. A microscope according to claim 27 further comprisingapparatus operatively associated with the detector and the scanner, forstoring and analysing a signal from the detector and a signal from thescanner, which, in use, is indicative of the location of the entitybeing moved by the scanner, to provide information in respect of theobject.
 31. A microscope according to claim 1, wherein said energysource comprises a source of electromagnetic radiation with a wavelengthin the range of and including far UV to far IR and wherein said energyguide is an optical fibre.
 32. A method of scanning an object to provideinformation thereof comprising:(a) focussing light from the core at theenergy exit of a single mode energy guide comprising a core, an energyreceiver and an energy exit, into a diffraction limited spot patternvolume having a central portion which intersects the object; (b) imagingthe core onto the central portion of the volume and thereby collectingoutgoing energy resulting from interaction between the light in thevolume and the object, wherein the numerical aperture, NA, of theoutgoing energy originating from the central portion focussed onto thecore, the wave length of the outgoing energy, λ, and the averagediameter, d, of the core at the exit end are related by the equation:

    NA≲0.6×λ/d

c) detecting the outgoing energy entering the core at the exit end toprovide a signal indicative of the interaction; d) refocussing lightfrom the core at the energy exit of a single mode energy guide to focusat least a portion of the central region in another volume intersectedby the object; e) repeating steps (b) and (c); and f) repeating steps(d) and (e).
 33. A method of scanning an object according to claim 32wherein said numerical aperture, NA, of the outgoing energy originatingfrom the central portion focussed onto the core at the exit end, thewavelength of the outgoing energy, λ, and the average diameter, d, ofthe core at the exit end, are related by the equation:

    NA<0.6×λ/d.


34. A method of scanning an object according to claim 32 furthercomprising storing and analysing the detected signal to provideinformation in respect of the object.
 35. A method of scanning an objectaccording to claim 32 further comprising storing and analysing thedetected signal and the position of the volume with respect to theobject to provide information in respect of the object.
 36. A method ofscanning an object according to claim 32 wherein said energy guide is anoptical fibre and the illuminating and outgoing energy iselectromagnetic radiation with a wavelength in the range of andincluding far UV to far IR.
 37. A diffraction limited confocalmicroscope comprising:a light source to provide focussable illuminatingenergy; a single mode energy guide comprising a core, an energy receiverand an energy exit; the energy guide being operatively associated withthe light source so that illuminating energy from the light source isreceived by the energy receiver and coupled into the core and guided tothe energy exit so as to emerge from the core at the energy exit; afirst focusser operatively associated with the energy exit to focus atleast a portion of the illuminating energy emerging from the core intodiffraction limited spot pattern volume having a central portion whichis use intersects an object; a second focusser operatively associatedwith the first focusser, and in use with the object, to collect outgoingenergy from the volume resulting from interaction between theilluminating energy in the volume and the object and/or resulting fromtransmission of illuminating energy through the volume; a detectorhaving an aperture and a detecting element; wherein the detector isoperatively associated with the second focusser whereby the secondfocusser images the central portion onto the aperture, whereby thedetector detects the outgoing energy.
 38. A diffraction limited confocalmicroscope according to claim 37 wherein the numerical aperture, NA, ofthe outgoing energy originating from the central portion imaged onto theaperture, the wavelength of the outgoing energy, λ, and the averagediameter, d, of the aperture are related by the equation:

    NA<0.6×λ/d.


39. A diffraction limited confocal microscope according to claim 37wherein said aperture is a pinhole aperture.
 40. A diffraction limitedconfocal microscope according to claim 37 wherein said aperture is thecore at an energy receiving end of a second energy guide having a corewhich also has an energy exit operatively associated with said detectingelement to detect outgoing energy focussed into the core of the secondenergy guide.
 41. A diffraction limited confocal microscope according toclaim 40 wherein said second energy guide is a single mode energy guide.42. A diffraction limited confocal microscope according to claim 37further comprising an energy splitter provided in the energy pathbetween the core at the energy exit and the volume to direct theoutgoing energy to the detector, and wherein the illuminating andoutgoing energy paths are substantially the same between the volume andthe splitter.
 43. A diffraction limited confocal microscope according toclaim 42 wherein the first focusser and the second focusser have commonenergy focussing elements.
 44. A diffraction limited confocal microscopeaccording to claim 42 wherein said energy splitter comprises awavelength dependent splitter.
 45. A diffraction limited confocalmicroscope according to claim 42 further comprising a polarizer,operatively associated with the energy source, to polarize theilluminating energy and wherein said energy splitter is polarizationdependent.
 46. A diffraction limited confocal microscope according toclaim 45 further comprising a polarization device disposed in the pathof the polarized illuminating energy and the outgoing energy between thepolarization dependent energy splitter and the volume to at leastpartially circularly polarize the illumination energy and to at leastpartially linearly polarize the outgoing energy passing back through thepolarization dependent energy splitter.
 47. A microscope according toclaim 37 further comprising a scanner which in use is operativelyassociated with the object to move the object in the x and/or y and/or zdirections to scan the volume in and about the object.
 48. A microscopeaccording to claim 47 further comprising apparatus operativelyassociated with the detector and scanner for storing and analyzing asignal form the detector and a signal from the scanner which, in use, isindicative of the location of the entity being moved by the scanner toprovide information in respect of the object.
 49. A microscope accordingto claim 37 further comprising apparatus operatively associated with thedetector for storing and analyzing a signal from the detector to provideinformation in respect of the object.
 50. A microscope according toclaim 37 wherein said energy source comprises a source ofelectromagnetic radiation with a wavelength in the range of an includingfar UV to far IR and wherein said energy guide is an optical fibre. 51.A diffraction limited confocal microscope comprising:a light source toprovide focussable illuminating energy; a single mode energy guidecomprising a core, an energy receiver and an energy exit; the energyguide being operatively associated with the light source so thatilluminating energy from the light source is received by the energyreceiver and coupled into the core and guided to the energy exit so asto emerge from the core at the energy exit; a first focusser operativelyassociated with the energy exit to focus at least a portion of theilluminating energy emerging from the core into a diffraction limitedspot pattern volume which in use intersects an object; a second focusseroperatively associated with the first focusser, and in use with theobject, to collect outgoing energy from the volume resulting frominteraction between the illuminating energy in the volume and the objectand/or resulting from transmission of illuminating energy through thevolume; a detector having a detecting element; wherein the detector isoperatively associated with the second focusser whereby the secondfocusser images a central portion of the illuminating energy in thevolume onto the detecting element, whereby the detector detects theoutgoing energy.
 52. A diffraction limited confocal microscope accordingto claim 51 wherein the numerical aperture, NA, of the outgoing energyoriginating from the central portion imaged onto the element, thewavelength of the outgoing energy, λ, and the average diameter, d, ofthe element are related by the equation:

    NA<0.6×λ/d.


53. A diffraction limited reflection confocal microscope comprising:alight source to provide focussable illuminating energy; a single modeenergy guide comprising a core, an energy receiver and an energy exit;the energy guide being operatively associated with the light source sothat illuminating energy from the light source is received by the energyreceiver and coupled into the core and guided to the energy exit so asto emerge from the core at the energy exit; a focuser operativelyassociated with the energy exit to focus at least a portion of theilluminating energy emerging from the core into a diffraction limitedspot pattern volume having a central portion which, in use, intersectsan object to collect outgoing energy resulting from interaction betweenthe illuminating energy in the volume and the object and to direct atleast a portion of the outgoing energy into the core at the energy exit;a detector; and an energy emanator operatively associated with the guideand the detector to extract the outgoing energy from the core and directthe outgoing energy to the detector; wherein the focusser images thecentral portion onto the core at the exit end.
 54. A diffraction limitedreflection confocal microscope according to claim 53 wherein thenumerical aperture, NA, of the outgoing energy originating from thecentral portion imaged onto the core at the exit end, the wavelength ofthe outgoing energy, λ, and the average diameter, d, of the core at theexit end, are related by the equation:

    NA<0.6×λ/d.


55. A diffraction limited reflection confocal microscope according toclaim 53 further comprising a scanner operatively associated with theenergy guide to move the energy exit in the x and/or y z directions toscan the diffraction limited spot pattern volume in and about theobject.
 56. A diffraction limited reflection confocal microscopeaccording to claim 55 wherein said scanner is a piezoelectric stack, amagnetic core/magnetic coil combination, a mechanical vibrator, anelectromechanical vibrator, a mechanical or electromechanicalpositioning mechanism or an acoustic coupler.
 57. A microscope accordingto claim 55 further comprising apparatus operatively associated with thedetector and the scanner for storing and analyzing a signal from thedetector and a signal from the scanner which, in use, is indicative ofthe location of the entity being moved by the scanner to provideinformation in respect of the object.
 58. A diffraction limitedreflection confocal microscope according to claim 53 wherein thereceiver and the emanator have an energy splitter in common whichenables a portion of the illuminating energy from the source to bedirected into the core of the energy guide and enables a portion of theoutgoing energy in the core of the energy guide to be directed to thedetector.
 59. A diffraction limited reflection confocal microscopeaccording to claim 58 wherein said energy splitter comprises awavelength dependent energy splitter.
 60. A diffraction limitedreflection confocal microscope according to claim 58 further comprisinga polarizer, operatively associated with the energy source, to polarizethe illuminating energy and wherein said energy splitter is polarizationdependent.
 61. A diffraction limited reflection confocal microscopeaccording to claim 60, further comprising a polarization device disposedin the path of the polarized illuminating energy and the outgoing energybetween the polarization dependent energy splitter and the volume to atleast partially circularly polarize the illuminating energy and to atleast partially linearly polarize the outgoing energy passing backthrough the polarization dependent energy splitter.
 62. A diffractionlimited reflection confocal microscope according to claim 58 whereinsaid energy splitter comprises an energy guide coupler.
 63. Adiffraction limited reflection confocal microscope according to claim 62wherein said energy guide coupler is a fused biconical taper coupler, apolished block coupler, a bottled and etched coupler, a bulk optics typecoupler with fibre entrance and exit pigtails or a planar waveguidedevice based on photolithographic or ion-diffusion fabricationtechniques.
 64. A diffraction limited reflection confocal microscopeaccording to claim 53 comprising an energy scanner operativelyassociated with the energy exit and the focusser to move the image ofthe core at the energy exit relative to the focusser to scan the volumein and about the object.
 65. A diffraction limited reflection confocalmicroscope according to claim 64 wherein the energy scanner is a movableenergy reflector, an electro-energy device or an acousto-energy device.66. A diffraction limited reflection confocal microscope according toclaim 53 further comprising a scanner operatively associated with thefocusser to move the focusser with respect to the energy exit to scanthe volume in and about the object.
 67. A diffraction limited reflectionconfocal microscope according to claim 53 further comprising a scanneroperatively associated with the energy exit and the focusser to move thecombination of the energy exit and the focusser with respect to theobject to scan the volume in and about the object.
 68. A method ofscanning an object to provide information thereof comprising:(a)focussing light from the core at the energy exit of a single mode energyguide comprising a core, an energy receiver and an energy exit, into adiffraction limited spot pattern volume having a central portion whichintersects the object; (b) imaging the central portion of the volumeonto the core at the energy exit thereby collecting outgoing energyresulting from interaction between the light in the volume and theobject; (c) detecting the outgoing energy entering the core at the exitend to provide a signal indicative of the interaction; (d) refocussinglight from the core at the energy exit of the single mode energy guideto focus at least a portion of the central region in another volumeintersected by the object; (e) repeating steps (b) and (c); and (f)repeating steps (d) and (e).
 69. A method of scanning an objectaccording to claim 68 wherein the numerical aperture, NA, of theoutgoing energy originating from the central portion imaged onto thecore at the exit end, the wavelength of the outgoing energy, λ, and theaverage diameter, d, of the core at the exit end, are related by theequation:

    NA<0.6×λ/d.


70. A method of scanning an object according to claim 68 furthercomprising storing and analyzing the detected signal to provideinformation in respect of the object.
 71. A method of scanning an objectaccording to claim 68 further comprising storing and analyzing thedetected signal and the position of the volume with respect to theobject to provide information in respect of the object.
 72. A method ofscanning an object according to claim 68 wherein said energy guide is anoptical fibre and the illuminating and outgoing energy iselectromagnetic radiation with a wavelength in the range of andincluding far UV to far IR.